Automatic train control



Dec. 6,-1932. D. H. SCHWEYER 1,890,419

I AUTOMATIC TRAIN CONTROL Filed Nov. 10, 1931 Patented Dec, 6, 1932 v Myinvention relates to improvements in mmssmT-ES ANI L' ERBER soHwEYEn,'or 'nns'ron, EmI's VANIA AUTOMATIC TRAIN ooivrnon Application file dliovember '10; 1931. Serial N0.1574,188.1

automatic train control and has to do, more particularly,withtrain-carried receivers and the trackway means by which conditionsare transmittedtheretog, v f r Several serious problems have been foundtoexist in connection with inductive receivers in present use. Becauserails are made of steel, trackway armatures must be spaced from therails a considerable distance,-and in order that a minimum amount ofinterfer ference be had from crossovers and switches, it has been foundpreferable to dispose the trackway armature outside of, and parallel tothe track; ;The mostcommon systems of inductive train, control now inuse operate either upon the principle of inducing current in relayenergizing coils gcarried by the train, or upon the principle of chokingthe'winding 0 upon an open core on the train byibridging the core gapwith'a trackway armature having an 'open-circuited winding.v In, orderthat such systems operate properly, extremely accurate adjustments, andhighly sensitive electro-responsive control and indicating devices mustbe employed. In such systems theindicative current variations generated,or

suppressed are often extremely smalland, vary greatly in accordance withthe speedof vthe train at the time of passage over the trackway elementso that, adjustments, at

best, can be made only with "average train speed as theirbasis. A train,thusequipped,

movingover a tralckway armature at extreme.- ly low speed, sayiive mlesper hour, might pass into a danger block vwithout IGCBIYIIIg anyindication whatever-of such condition.

And an automatic safety device which isnot 100% operativeunder everypossible ,conditionis not only ineiiicient,fbut, because of ithereliance naturally placed thereon, is a'menace. worse than no safetydevice at,

to safety and all. I i

With these and other factors injmind, my

invention has for its purpose the accomplishment of several well definedobj ects. 1 p

The primary object ofmy invention is to provide-a traincontrol systemwhich is more sensitive than. systems heretofore in use,

. Another object of my. invention is to pro,- v

9 I A'furtherobject-ofImyinventionisito proof a preferred form of myinvention as em ing three poles adapted. Iran coaction "with vide atraincontrol system which will operate'uniformly and accuratelyregardless of whether the train be travelingat high, mod-- erate, orextremely lowspeed. v a i vide a'train-carrijed receiver which is simpleinconstruction,positive inaction, unlikely require frequentadjustment','inexpensive to manufacture, andi lowi 1n current-consumpFurther eration will definitely appear fromi the "def tailed descriptionto follow,- In onefinstanc'e I accomplish the objects-of my'linventionbyi .the devicesand means set fprthvin'thejfollgwg ing specification. 1'My invention is clearly gdefined] and pointed out in the appendedclaims; Structures constituting preferred embodiments of 'my'inventionar i1 1 tmt 7o i in the accomp nying drawing forming apart of thisspecification, inwhich: i

Figure l -is a diagrammatic representation bodiedin apparatus includinga three-pole 11 train-carriedreceiver core and atwo-poleflux-shuntingtrackway armature; Fig.2 'sa diagrammatic representation of analternateform of trackway armature havthe three pole pieces.*0ftrain carriedequipment such as shown in Fig; ,1; i r V Fig.3 isa'diagrammaticrepresentation of a modified form ofmy invention asembodied in afour-pole H type :receiver' core; a; a

,FigAisa diagrammat-ic'representationsof i a modifiedform ofmy-inventionas adapted for operation with aTsingle A. 'C. source, and 7showing a modified form trackway means; and I 90' Fig; 5'is adiagrammatic representation of I still" another modification of myinvention in Wl'llChf-h receiver core is normally magnet ized byvDQC.and the control or indicating;

latediby the trackway armature. I In the drawing the same referencenumerals refer to the'same or similar parts throughout theseveral'viewsn' r P v v; objects and objects relatingto detailsand'economiesj of construction and op-f 1 of flux shunting device isenergized only upon the occurrence of -.a changed trackway conditlonastrans i V Referring now to the numbered parts ofmy drawing,'and moreparticularly to Fig. 1 thereof, there is diagrammatically illustrated atrain-carried receivercompris'ng a threeleggedsyoke or core 10, ontheouter legs 11, and 13 of which are disposed coils l4 and 15' vwhichareso wound and connected to the A.

-C. 'source16'as to 'j'ointiyset u'p" flux in the core 10. The middleleg 12" is at the flux centerof the: core and therefore is'substantiallyfree froin fiux setup by coils 14 and 15. I An impulse coil 17 is'dsposed: around; leg'12 and a low power D. C. source 18' and 1 aholding relay 19 are connected in. series with coil 17. Associated withrelay 19 and held'closed so long as the relay circuitfre mainsuninterrupted, is an indicator orcon trol c1rcu1tjco'mpr1singa relaycontrolled;

switch arm 20, a source of cur'rent'21, "and a signal device orelectro-energized'.brake control 22. A trackway-mount-ed' element forinfluencing. the train-carried receiver in accordancewithtrackwayconditions comd prises a core 23 having'upstanding' arms its ends, achoke winding 24 intermediate its ends, andia relay'ors-witch 25 foropening 3 r or closing vthe' choke winding infaccordance with trackwayconditions; The circuits for operating relay25 may be conventional and I"are therefore not illustrated.

'. The operation a of the"apparatus shown in Fig. '1 is as follows,Alternat ng current generated by theA. C; source, 16 energizes coils 14and 15, j'settingu'p a flux in core :10 as though it were of simple U'frmQ-that' is, middle leg 12 issubStantiaIlyfreeifrom A. C. flux. Impulsewinding-1'1 on leg 12 therefore normally has no [current induced[therein and under such circumstances serves merely to completethe'circu t connecting the .weak D. C. source 18' to the relay 19 whichan open circuitedwinding 2'4, the-tra'n-car-c Fried receiver willbeunafi'ectedp However,

when the train-carriedfreceiver' passesove'r a trackway core 23 having awinding 24 which isn'otclosed bythe switch 25, that is .to say, overatrackway armatureactuated toiind catea caution or danger condition,

fstrong A, C. flux isishunted through the trackway core 23 and themiddleleg'12superposing and neutralizingthe weak fiux set up in the leg.12 bythe weak D. C; source 18,

I and by. transformer action tendingto setup l (it) most, acoinpletecycle of alternating current an alternating current in impulse winding17. v.HoWever, superposition of" one-half, oi at in w nding 17 willprov'i'dea momentary ces sationof current flow throughthe winding ofrelay 19 and allow relay'arm 19a and sw tch arm to drop, properlycutting on,

source of current 21 from-the indicator or" indication or theapplication of brakes.

control device 22-and providing a w r i '3 i V In Fig. 2 there is showna three-armed trackway element having two choke wind-j I lngs which maybe used in'place oi. the twoarmed trackway element shown in Fig. 1. In 7this embodiment there is a three-armed core I26v having outer arms 27and 29 and a middle arm 28. A pair of choke windings 30, 31, on the bodyof the core 26, are controllable singly, or in multiple, by the relay32which is, in turn, controlled by a conventional track-,

way block indicating circuit.

'In Fig.3 there is showna somewhat modified form of train-carriedreceiver embodying my invention whichcomprises a core 33.

of;H 'form, upon the central bar 34 of which i's wound-a coil 35 whichis' energized by a comparatively strong D.]G. source 36; no

Pair of Opposed rms 37, 38, extend downwardly from thecentra bar 34of'theio fe" and terminate'in feet 37a and 38a,which are, 7

rather widely spaced from each other pro- H I viding an air gap A andthus constituting; with central bar 34, "a flux circuit of rather:

high reluctance. A- second pair'of arms39,

40,,branch from the'end's ofthe middle bar 34 and terminate-opposing"each' other across'an -air gap B of less width than gap Aand'constitute,with central bar 34, a flux circuit of lower reluctancethan the aforementioned flux circuit including airl gap I Impulse coils41,42 are connected in series in a relay circuitwhich includes a holdingrelay 43-and J a" comparatively wea,k=D.; C. source 44.

. D. C. source 44-is so connected in the-relay circuit that the flow ofcurrent, which would bemoinentarily in'ducedin' coils 41, 42'uponconnection of D. Gtsource 36 to coil 35, would i augment said D. C.source44. Thus, and in versely, disconnection :of the strong" D; C.

source 36 from-coil35 would result in a current kick momentarilyovercoming the weak current made to flow'in the relay circuit by I 3Weak DLIG. source44.

The operation of th'e apparatus shown in" Fig. 3 is as follows- Solongras the train and i its receiver does not pass over the- 'trackwayelement havlng an open w1nd1ng,D'. G.source '36 will energize coil .35,setting upfiux in the flux circuit comprising central bar 34,- arms39yand4O and air gap B. Little or no flux will be set, up in the circuitincluding arms-37,

"38'and air-gap A, because of its'greater reluctance; Once the D; C.source 36 has been connected tocoil 35, no current will "be ,in-

duced in coils 41, 42, and the weak D. C.

source '44will" maintain relay (43 stuck and theindicatororcontrolcircuit energized so long as clear trackw'ay cond tionscontinue to BX7S11. However, upon the passage-of the feetq37a,38aof-thereceivercore 33 over a trackway core 23, having a choke winding 24open-c'ircuite'd by a relay 25, core fluxsetup by coil is immediatelyshunted through the clrcuitwhich includes legs 37, 38 and gap A bridgedby core 23. The flux circuit including legs 39, 40, is thus instantlyrobbed and a current kick is set up in coils 41,42, which is strongerthan, opposed to, and overcomes the normal currentflow effected by D. C.source 44. Relay 43 allows the arms43a and 20 to fall, therebyappropriately. indicating" the danger condition or setting the train-.brakes.

. In Fig. '4 there is shown a similar type of receiver'adapted forenergization and operation with a'single A." (l-source, As in the formshown in Fig. 3, there is an H type receiver core 33, having twopairs ofopposed "arms 37,38 and 39, 40, the air gap 39 and and are connected inseries to enera gifze A. C. holding relay 53 with current inducedin'coils 51, 52.- A somewhat modi fied trackway armatureisshown inFig.4, which armature comprises astralght bar'or core 123 having no'legsand wound for sub- Q stantially'its entireextent with a choke winding orcoil 124. The conventional relay 25 controls the opening and closing ofthe choke winding as in the other trackway elements shown. One advantageof the form of track'- way armature shown'in Fig. 4 is that there is aminimum offlux leakage around the winding 124. f

The operation of the apparatus illustrated in'Fig. 4 is as follows. A.C.source.56 constantly energizes coil 55, setting up flux in the centralbar 34 of the core which flux normally passes through the flux-circuitincluding arms 39, 40, and air gap B. Alternating current i's thusinduced in coils 51, 52 on I arms 39,40 and such currentmaintainsholding relay53 energized :to hold relay arms 53a and 20closedand thus properly control indi eating orbrake' setting device 22.However,

under danger conditions, relay 25iopensthe choke winding 124 ofthe-trackway armature causingcore 123 to constitute a flux bridge forthe air gap A. The flux circuit includ:

ing arms 37, 38 and air gap Atherebv becomes of lower reluctance thanthe c1rcu1t including arms 39,40 and air gap 13. Flux is thus shuntedfrom the coils 51, 52, and little or no current is induced therein withthe result that relay arms 53a'and20 fall and the danger indication isgiven, or the brakes are set, or both, depending upon the nature andconstruction of'the element 22, which may take many forms. j i i f In 5there ,1s "shown a somewhat modified form of receiver embodyingmv-invention and adapted for operation with a single D. C. source. Q Asin the form show-n in Figs. 3 and4, there is an Htype-receiver core 33having two pairs o f op'posed arms 37, a l

38 and 39,40, the air gap Act which is wider than the air gap B. Afcoilidisposed upon the central bar34 of the core'and is energized by all C.source-64, magnetizing eludes arms 40 and airgap B. Impulse coils-61, 62disposed onarms'39 and 4Qpare connected in series tothe magnetic relay63 having a normally closed relay c1rcu1t arm the core circuit of lowerreluctance which in- 1 63a and a' control or' indicator circuit arm 120which is'closed in the absence of current flowin the relay circuit andmaintains "the indicator or co'ntr'ol'currentsource 21100111,

Fig. @5'LlS as follo'ws. So long as the train does not'pass overatrackway armature core= nected to the'indicator or control device 22.]Theoperation of the receiver shown in 23'having a choke winding 24whichisopen' circuited, as by the relay 25, the arms 39, 4'0 y willremain magnetized by D. C. flux set up by coil Should, however, thetrain pass 0 over an open circuit'ed windingfl24 andits core 23,-thearms 39, 40 rwillbe totally, or at least largely demagnetiz'edby reasonof 1' shuntingofthe flux into'thefci'rcu-it including a-rmsj37,38 andcore 23. ,A current kick" V will thus be'generated'in coils 61,62 andthe electromagnet of the relay 63 willmomenw tarily lift thearm'120,'*breaking oil the current source 21 fromthe indicator orcontrol device 22.

In equipment of'jthe character above described, where the current whichefiects change in theelectroresponsive indicating or control. device 1sprovided byinduction in a secondary coil through which" flux passes.only wh'enfthe receiver core is'bridged by the trackwayelement, it isvital that such.

bridging exist for a space of time sufi'icient to cause a substantialcurrent to be I In the form of track'way' elementshown inFigZ" 4,adequate bridging Ia's'sured; even induced in ,the secondary coil.

at ..exceptionally high speeds vand coil'55. due tothe elongateformofthe'core 123. The same istrue of the formcftrack way element showninFig. 2. By way of .with allowfrequency current source for theillustration, should thereceiver shown in Fig. 1 be used with a very lowfrequency current form there shown, and should thertrain be .16 and avery small trackway element of the traveling at a very high speed itmight happen that the legs 11-, 12 of the core 10 would completely-passover the core-23 -during-the' moment when the. sine wave ofthealternat-. ing current flowing incoils 14 and :15 was at its crest. Inthat eventthe currentinduced' incoil 17 would be negligible andins'ufiicient to effect dee'nergiza'tion *or 1 the electro-responsiivedevicel9. Usingthe form of track- 7 wayelement shown in Fig; -2, -=itwouidbe sud re cl impossible for the receiver coreQlOlto clear thei'core26dur1ngjthe moment thecurrent. wave Wasat 'lllS crest.

q 1 'lVhile Ihave disclosed what, I regard tobe preferred embodiments ofmy invention, such are illustrated primarily forthe purpose ofexplainingthe inventiomand are by no means to lie-regarded as the only forms inwhich it is capable of embodiment. Numerous variations will appeal tothose skilled inthe.

who become familiarwiththe concepts ot thepresent invention. Forexample, while 1 have disclosed choke-wound trackway element whicheffects br dging or shunting of a flux path of high reluctance by reasonof open circuiting its winding, it is obviousthat such br dging -mightbe accomplishedbyan unwoundbar of magnetic material and might becontrolled by posit-ioning'the barwith respect to the line of thereceiver core. While I have shown electromagnetic relay elements '25, 32for operating thechoke circuitrswitches, it is to be undei'stood thatother equ'ivar 'lent means,'manual, or mechanical night be used. WhileIhave'found it preferable, in

order to avoid interference by cross-oversand I switches to so mount thetra'ckway receiver core uponthe train thatiit hangssome ten or twelveinches outside of the rail and cooperates with a tr'ackwayi-elen'ientdisposed] approximately two andone-lialfinches above the rail, undercertain conditionsfltmight be desirable to dispose the receiver core andtrackway armatures transversely of the traokway. Similarly, while I havevaried the reluctance of the several flux circuits of the core by makingair gaps therein of different widths, other methods suchas-usingdifiier- ,"ent corematerials, difi erent core cross, sec

tion or auxiliary'choking means might be substituted' Further, whileIhave referred to the control current as alternating in character it isto be understood thatthisterm is intended to include anysuitable-fluctuating current. andis not restricted to" any specific,frequency,

since theiapparatus will operate on frequen- I cies lower than ;cyclesper second or higher eventhan- 360 cycles per second. Likewise, while Ib ave shown in Fig. 1, a pair of coi s connected in parallel to theA.C;- sourc'e,.it is obvious that suchcoils, wound to diifer'entiallypolarize the core, may be connected in series if desired. If-desired,additional coils may be placed upon the legs 11 and 23 of the Idevice'shown in Fig. 1, so as to operate as a "two-phase or three-phasesystem. -,Mo reove r,

7 -;.for the purpose of positively opening the re- I lay in thesecondary circuit of the form of apparatus shown in Fig. lyFigQ 3 orFig." 4,

should the primary; current source fail, a

v safety relay maybe incorporated consisting of an electro-m'agneticelement in :the pri- 5 'Inary circuit and a switch arm actuated therebywhich controls continuity of the secondary v those skilled in the art;

circuit. Numerous other variations within.

the scope .of this invention will appeal to 'It-isto be understoodtthatwhile the present invention is disclosed as embodied in a simple traincontrol system indicatingonly clear or danger conditions, iits conceptis readily capable of embodiment in'counting "pr translating traincontrol systeins and even in apparatus; for performing other. functlons,

for example, exploring systems for indicating the presence of hiddenmagnetic bodies. I 1 Lthereforeyclaim my invention broadly asindicatedby th'e appended claims.

WhatI'claimiszi' ,2 1. In a train control'system, atrain-carried'receiver including 'a magnetic core, a

constant. current source, winding on said core' I energized by saidconstant currentfsourceand settlng up normal flux'd1'str1but1on-1nsa1dcore, an electric-responsive control, orindieating device, a secondwinding. on said core,v

saidsecond windingbeingso arranged with 1 respect to the normaldistribution of flux in said core and so electrically associatedwithsaid electrosresponsive jdevicethat saidi des vice remains undisturbedduring andonly dur ng the existencejof. sald normal flux} distributionin" said vcore and altrackwaywith respect to said receivercbut'renderedeffective in accordance with-adversetrack:-'

way conditions-to. shunt away ala-rge portion of the. flux normallyexistent in one coil on eachof the-outerlegs of said yoke.

energized bysaid A. C. source,'said coils beingso wound with respect toeach other thatthe middle leg of the yoke isnormally neutral or freefrom-fluxrs'et up by. said coils, I

an impulse coil onfsaid [middle leg, an electro responsive control orindicating device,

and a source of current weaklyfenergizing said device and lmpulsec011,.sa1dv last mentioned current source being out offphase' with.

said'first mentioned A; C. source and a track,-

way-mounted armature ofmagnetic material normallynon-influentialwithrespect to said rece ver. but rendered effective 1n accordance withadverse trackway condltlonsj to mag.-

. netically bridge the space between the middle g leg and an outer legofthe yoke thereby di-fvertingyoke flux generated byjthe' coilojn',

that outer leg through said middle leg causing current to' be induced insaid impulse coil which is out. of phase with andiovercomes the currentnormally energizing. said electro-responsive control or -indicating device.

mounted. armature normally-non-influential 9" 3. In a train controlsystem,.,a train-carried receiver comprising a three-legged yoke ofmagnetic material, a source of A. (l,- a coil on each of the outer legsof said yoke energized by said A. C. source, said coils being so woundwith respect to each other that the middle legof the yoke is normallyneutral or free from flux set up by said coils, animpulse coil on saidmiddle leg, an electroresponsive control or indicating device and asource: of D, C. weakly energizingsaid' device and impulse coil; anda'trackway-- mounted armature of magnetic material nor;

mally non-influential with respect to said receiver but renderedefiective in accordance with adverse trackway conditions to mag-jnetically bridge thespace between the middle. leg and an outer leg ofthe yoke thereby di verting yoke flux generated by the COiI on thatouter leg, through said middle leg in ducing A. C. in said impulse coilwhich overcomes the D. 0.. normally energizing said eleetro-responsivecontrol or indicating device. 4. In a train control system, atrain-carried receiver comprising a three-legged yoke of magneticmaterial, a source of A. G., a,

coil on each of-the outer legs ofsaid yoke] and connected in parallel tosaid A. C. source,

said coils being so wound with respect to each other that the middle legof the yoke is normally neutral or free from flux set up by said coils,an impulse coil on said middle leg, anv

electro-responsive control orindicating device, and a source of currentweakly energizing said device and impulse coil, said last mentionedcurrent source being out of phase .with said first mentioned A. C.source; and

a trackway-mounted armature of magnetic material normallynon-influential with respect to said receiver but rendered effective.

in accordance with adverse trackway conditions to n'agn'etically bridgethe space between the middle leg and an outer leg of the yoke therebydiverting yoke flux gener-, ated by the coil on that outer leg throughsaid middle leg causing current to be induced in: said impulse coilwhich is outof phase with and overcomes the current normally energizingsaid electro-responsive control or indicating device. v I i I 5. Inatrain control system, a train-carried receiver comprising a three-leggedyoke of magnetic material, a source 0 connected in parallel to' saidA.C. source,

said coils being so wound with respectto each other that the middle legof the yoke is nor; mally neutral or free from flux set up by saidcoils, an impulse coil on said middle leg,'ai1

electro-responsive control or indicating device, and a source of D, C.weakly energizing said device and impulse coil, said impulse 00.1 Fdevice, and D. C. source being connected in. "series; and atrackway-rnountedarmature of 0., a coil on each oi theouter legs of saidyoke and,

magnetic material normallynon-influential. with respe'ctto saidreceiverbutrendered efor v I .fective in'accordance with adverse trackway conditions to magnetically bridgethe space between the middle-leg andan outer leg of the 'yokethereby diverting yoke flux-generated by thecoil on that outer leg. through said middle leg, inducing A. G. in saidimpulse i J coil which overcomes the. D. C. normally energizing saidelectro-responsive. control or indicatingdev ce i 6. In a traincontrolsystem, atrain-carried connected inparallel to "said .A,

each otherthan the middle ,leg'of the yoke is normallyneutral or free,from; flux set up by said coils, ani npulse coil on said middle leg, anjelectro-responsive control or, indicating device, and a source of D. C.'weaklye iergizing said device and impulseicoik-said impulse coil,device, and D. C. source being. con--.

nected in series; and attrackway condition transmitting elementcomprising a core of magnetic material of such length and so disposedwith respect to the plane of the receiver yoke as to constitute a fluxbridge diverting yoke flux generated byanouter leg coilthrough themiddleleg of the yoke in d'ucing A. C. in said impulse coil powerful,enough :to overcome the D, C. normally energizing saidelectro-responsive control or in- Cl1Cit1I1gd8V1CQ,aI1d a choke windingon the core of said trackway element which when receiver comprising 'athree-legged yoke of 'magnetic material, a sourceof A; 0. a coil. oneach of the outer legs of said joke and V source, said coils being sowound with respect to; 7

closed renders said core inoperative asa flux bridge forsaid yoke. i

7. In a train control system, a train-carried receiver comprising aconstant currentsource,

a coil connected-to said current source, a core of magnetic materialhaving a trunk portion disposed through said coil and energizedtherebyandbranches at the ends of said trunk j portion ,which branchesdefine two distinct circuitsfor the flux set up in saidcore, one. ofsaid circuits having less reluctance than the other circuit andnormally'constituting thepreferred an m P for the flux? an electro-responsivecontrol or indicating device, and an impulse coil wound around thenormally preferred flux circuit, said last mentioned coil being soelectrically associated with said electroresponsivedevice that saiddevice remainsundisturbed during and only during the presenceof'iiormalflux in said preferred circuit; and a. trackway-Y mountedv armaturenormally non-influential 8011 which was appidpi iia actuation; f the"elec'tro responsive "control or indicating device.

8. Ina train control system, a train-carried receiver comprising amagnetic 1" core of Hforin, one pair of opposed arms ofwhi ch; 1 aremore widely spaced than the other pair,

a" coil on the middle bar'vof said core, a constant current sourceenergizing said -j coil, an 'electro-responsivecontrol or indicatingdevice, and coils' on the pair of opposed core arms which are lesswidely spaced, said 1 arm a-trackway-mounted armature normallynoninfiuential with respect to said-receiver but "rendered effective inaccordance with adverse'tr'ackway con'ditions'to constitute a fluxbridge across the more widely spaced pair of opposedcore arms, th'usrobbing thGCOllS [on the other pairof opposed arms of the flux normallyexistent therein.

, 7 9; In atrain control system, a

train carried receiver comprising a inagnetic core of H 'form, one pairof opposed armsflof which-are more widely spaced than the other {pa1r, a

' coil on the middle bar of said core, a constant currentsourceconnected to and energizing said coil, an electro-responsiv'econtrol "or1111 dioating device, coils onthe pair 'of core arms which areflesswidelyfspaced, and; a source ofDQ, C. .weakly energizing'said' coils andelectro responsive device; and a" trackway mounted armature normallynon-influential with respect 1 to said receiver but ren'dered' 7effective inaccordance with adverse trackway conditions to constitute afluxibridge across theimore widely spaced pair of opposed core arms,thusrobbing the coils" onthe less widely spaced pair of'opposed armsofthe flux normally existent therein and causing a: current kick in saidcoils which opposes the D. C. energizing the electro-responsive device:V i

10. In a train control system, a traincarried receiver comprising amagnetic' core control or indicating; device, a second, and

i of H-form, onepair ofopposedarms of which 7 are morei-widely spacedthan the other pair,

a coil on the middle bar of said core, a main source of D; connected tosaidco l and polarizing said core, an electro-resp'onslve comparativelyweak source of D.CQ, and coils on'said less widely spaced pair of.opposed,

V tinct circuits forthe flux setup in said'core,

7 "core arms which areso connectedin' .a series 'circuitw th said devceand said weak D; C.

source that the flux setiup. in said less; widely spaced arms by saidmain D; C; source is augmented bythe flux therein setup by said .weak'D.C. source; and a trackway-mounted' armature-F normallynon-influentialwith rea H spect tosaid receiver but rendered effectivein accordance with adverse trackway'condi tions to" constitute a flux Ibridge across the more widely spaced pair ofiopposed core" arms, therebyrobbing the less widely spacedv arms of flux and generating in the coilsdis-, 76 7 posed thereon a current kick which opposes and overcomes theD. G. provided bysaid' weak D. C. sourceofenergizing said electroresponsive control or indicatingdevice. v '11. Ina train controlsystem,fa 13111111 carried receiver comprising a magnetic'core ofH-form,=one pair of arms of which are" more widely spaced than the otherpair, a coil 1 on the middle bar of said core, a 'sourceof V A. C.connected to'and energizing sa1d'-co1l,-

"an A.'C. li'oldingrelay governing a control of indicating circuit,relayener'gizingcoils on arms in which'clirrent is normally generatedby-A. .C. fluxfin said lesswidely spaced arms set. upby, the coil onsaid middle bar; and a said lesswid'ely spaced pair of opposed core"trackway moun'ted armaturefnormally non influential with respect to saidreceiver but.

renderedeflectivec-inaccordance with adverse o traekway conditions toconstitute a flux bridge across the more widely'spacedpair of opposedcore arms; thus shunting andare more widely spa ced thanthefl'otherpaina coil on the middlebar of said core, asource of D. G.connected'to-and' strongly magnetiz posed core-arms, a circuit openingrelay, impulse coils on said less: widely;spaced-core arms and connectedto sa1d'r'elay; and*a robbing the lesswidely spaced-pair ofcore" 7 armsof the flux by whichic'urrent isnor for energizing said A. hold 96 kl2ln a' train, 'control' system, a train," 3

.ing said bar andflthe less widely 'sp'acedop-f t'rackway-mountedarmature normally non influential with respect to saidreceiver butrendered effective in accordance with adverse tra-ckway conditions toconstitutea *flux' bridge across the more widely" spaced-j pair of corearms, thus shunting the fluxfthrough" the more widely spacedcorearms andinduc-f ing a current kick in said impulse;- coils by reason of thedropin fluxtherethrOugh.

a corev of magnetic material having a trunk? portiondisp'osedthroughsaid coil and energized thereby and branches atthe endsof said; trunkportion which branches define two dis-'- one of said circuits havingless reluctance;

than the other circuit andnormally consti-Y 5 V "flux, an"electro-responsive control "or .indi-i tuting' the preferred and mainpath forthe cating device, and an-impulse coil 'woundf f' around thenormally preferred flux circuit, 5

said last mentioned coil being so electrically 1' associated with saidelectro r'esponsive device that said device remains undisturbed duringand only during the presence of normal flux in said preferred circuit;and'a trackwayinounted armature normally non-influential coil whichcauses appropriate actuation of core arms which are less widely spacedand the electro-responsive control or indicating device, said trackwayarmature comprising a magnetic core and a choke winding on said corewhich when closed renders saic core ineffective as a flux shunt.

14. In a train control system, a train-carried receiver comprising amagnetic core of H-form, one pair of opposed arms of which are morewidely spaced than the other pair,

a coil on the middle bar of said core, a constant current sourceenergizing said coil, an electro-responsive control or indicatingdevice, and coils on the pair of opposed core arms which are less widelyspaced, said. arm coils being so electrically associated with saidelectro-responsive device that said device remains undisturbed while andonly while the main stream of the core flux passesthrough atrackwa-y-mounted armature normally noninfluential with respect to saidreceiver but rendered efiectifze in accordance with adverse trackwayconditions to constitute a flux bridge across the more widely spacedpair of opposed core arms,thus robbing the coils on the other pair ofopposed arms of the flux normally existent therein, said trackwayarmature comprising a magnetic "core and a choke winding on said core.which when closed renders said core ineffective as a flux bridge. V

15. In a train control system, a train-carried receiver comprising amagnetic core ot' H-form, one pair of opposedarms of which are morewidely spaced than the other pair, a coil on the middle bar of saidcore, a constant current source connected to and energizing said coil,an electro-responsive control or indicating device, coils on the pair ofcore arms which ar less. widely spaced, and a source of D, C. weaklyenergizing said coils and electro-responsive device; and atrackway-mounted armature normally non-influential with respect to saidreceiver but rendered effective in accordance with adverse trackwayconditions to constitute a flux bridge across the more widely spacedpair opposed core arms, thus robbing the coils on the less widely spacedpair of opposed arms of the flux normally existent therein and cans inga current kick in said coils which opposes the D. C. energizing theelectro-responsive device, said trackway armature comprising a magneticcore and a choke windingon' said core which when closed rendersisaidcore ineliectiveas a flux bridge. r

16. In atram control system, a-train-carried receiver comprising amagneticcore of H-form, onepair of opposed arms of which are more widelyspaced than'the other pair, a coil on the middle bar of said core, amain source of D. G. connected to said coil and polarizing said core, anelectro-responsive con.- trol or indicating device, a second, andcomparatively weak source of D. C., and coils on said less widely spacedpair of opposed core arms which are so connected in aseries-cir cuitwith said device and saiclweakDl C. source thatthe flux set up in saidless widely spaced arms by said'mainD. C. source is augmented by theflux therein set up byisaid weakD. C. source; and a trackway-mountedarmature normally non-influential withrespect to said receiver butrendered effective in'accordance with adverse trackway conditions toconstitute a flux bridge across the more widely spaced pair ofopposedcore arms, thereby robbing the less widely spaced arms of fluxand generating in the coilsdisposed thereon a current kick which opposesand overcomes the D. C. provided by said weak D. C. source of energizingsaid electroresponsive control or indicating device,said trackwayarmature comprising a magnetic core anda choke winding on sald corewhich when closed renders saidcore ineffective asa flux bridge.

17. In a train control system, a train-carried receiver comprising amagnetic core of H-form, one pair of arms of which. are more widelyspaced than the'other pair, a coil on the middle bar of said core, asource of A. 0. connected to andenergizing said coil, an A. C. holdingrelay governing a control of indicatice ing c1rcuit,'relay energizingcoils on said less 7 I v widely spaced pairof opposedcore arms in whichcurrent is normally generatedby A. C.

' flux in said less widely spaced arms set up by the coil on said middlebar; and a 'trackwaymounted armature normally non-influential withrespect to said receiver but rendered effective in accordance withadverse trackwayf conditions to constitute a flux bridge across' themorewidely spaced pair of opposed core arms, thus shunting and robbingthe less widely spaced pair of core arms of the flux by which current isnormally induced for energizing said A. C. holding relay, said trackwayarmature comprising a magnetic core and a choke winding on said corewhich when closed renders said core ineffective as a fiuxbridge.

18. In a train control system, a train-carried receiver comprising amagnetic core of 'H-iiorm, one pair of opposed arms of which are morewidely spaced than the other pair, a coil on the middle bar of saidcore, a source of D. C. connected to and strongly magnetizsaid bar andthe less Widely spaced op} posed corelarms, a circuit opening relay,11npulse coils onsaid less Widely spaoedicore v arms and connected tosaid relay; and a track Way-mounted armature normally JlOlI-lnfllbenti-al With respect to said receiverubut rendered effectlve 1naccordance W th adverse trackway conditions to constitute a flux bridgeacross the more Widely spaced pair ofcore arms, thus shunting the fluxthrough the more Widely spaced-core arms andindu'cing a cur rent kick'insaid impulse coils by reason of the :drop influx therethrough, saidtrackway armature comprisinga magnetic core and a choke Winding onsaidcore which When closed renders saidcore ineffective as a fluxbridge. DANIEL HERBERT SCHWEYEB;

as. F

